An interchromatin granule is a cluster in the nucleus of a mammal cell which is enriched in
pre-mRNA
A primary transcript is the single-stranded ribonucleic acid ( RNA) product synthesized by transcription of DNA, and processed to yield various mature RNA products such as mRNAs, tRNAs, and rRNAs. The primary transcripts designated to be mRNAs ...
splicing factors. Interchromatin granules are located in the interchromatin regions of the mammalian
Cell nuclei
The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, ha ...
. They usually appear as irregularly shaped structures that vary in size and number. They can be observed by
immunofluorescence microscopy.
Interchromatin granules are structures undergoing constant change, and their components exchange continuously with the
nucleoplasm
The nucleoplasm, also known as karyoplasm, is the type of protoplasm that makes up the cell nucleus, the most prominent organelle of the eukaryotic cell. It is enclosed by the nuclear envelope, also known as the nuclear membrane. The nucleoplasm ...
, active transcription sites and other nuclear locations.
Research on dynamics of interchromatin granules has provided new insight into the functional organisation of the nucleus and gene expression.
Interchromatin granule clusters vary in size anywhere between one and several micrometers in diameter. They are composed of 20–25 nm granules
that are connected in a beaded chain fashion appearance by thin fibrils.
Interchromatin granule clusters (IGCs) have been proposed to be stockpiles of fully mature
snRNP
snRNPs (pronounced "snurps"), or small nuclear ribonucleoproteins, are RNA-protein complexes that combine with unmodified pre-mRNA and various other proteins to form a spliceosome, a large RNA-protein molecular complex upon which splicing of pre- ...
s and other RNA processing components that are ready to be used in the production of mRNA.
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See also
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Cell nucleus#Splicing speckles are subnuclear structures that are enriched in pre-messenger RNA splicing factors
References
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Cell biology